Radius forming device



May 17, 1949. J, GOULETTE 2,470,097

RADIUS FORMING DEVICE Filed Sept, 27, 1945 FIG; l'.

5a A so 4s 4e 36 3s le 2o llss'/ lse /jo- AT TOR NEY Patented May 17, 1949 UNITED STATES PATE-NT OFFICE RADIUS FORMING DEVICE Joseph e.. Gelette, Newmarket, N. H. Application September 27, 1945, Serial No. 619,002

4 Claims.

(Granted under the act of March 3, 1883, as

This invention relates to a radius forming de vice 'and is illustrated herein as embodied in an attachment for a inetal working machine adapted fr use in turning or otherwise producing a sur face of the type commonly used as a ball race, the cross section of which is uniformly circular.

A surface of the type mentioned above may be machined by the use of a formed cutter which is 'adapted to be fed directly into the work to the required depth. Since this type of tool takes a chip as wide as the cutting edge of the tool is long, the tool has a tendency to chatter. At ordinary cutting speeds ksuch a tool also has a tendency to tear the finished surface. Both of these difculties may be minimized by employing 1 a relatively slow cutting speed; but in so doing the operation is unduly prolonged, and a final polishing operation is always necessary to impart the desired finish to the turned surface.

In View of the foregoing, the present invention provides a device adapted to employ a pointed tool which is moved orbitally so as to make a progressive cut from one side of the surface to be formed to the other, whereby the surface can be finished with the greatest possible speed and smoothness obtainable by turning. Since this type of operation does not produce chatter marks, or pockets which result from a tearing cut, the polishing operation is rendered very simple since only the ne and closely spaced tool marks need be removed.

In the illustrated device, the holder for the tool is moved in the manner described by a pair of cranks which are driven in synchronism with each other. To adapt the device for forming surfaces of diferent radii, the above-mentioned cranks are adjustable in eccentricty. This feature of the device, in which the invention is to be recognized, is afforded by lmounting the cranks eccentrically for adjustment in rotation on members which are rotatably mounted on the base of the device. Accordingly, by adjusting the cranks so that their eccentricity either contributes to or detracts from that of the members, the total effective eccentricity of the cranks may be varied throughout a substantial range. 4

With the above and other objects and features in view, the invention will now be described with reference to the accompanying drawings which illustrate a preferred embodiment of the invention and will be pointed out in the claims.

In the drawings: v

Fig. 1 is a plan view of an illustrative device embodying the invention.

Fig. 2 is a sectional elevation of the device shown in Fig. 1, the section being taken in a plane including the axes of the crank shafts.

Fig. 3 is an end elevation of the device shown in Fig. 1; and

Fig. 4 is a diagrammatcal View illustrating the adjustment of the radius of the orbital movement of the tool holder.

The illustrated attachment comprises a base IIJ having a hole i2 (Figs. 1 and 3) therein adapted to receive a bolt for securing the base to the carriage of a lathe or other machine tool. The base has a plane seat I4 (Fig. 3) on which a tool holder i6 is mounted to slide in any direction. The tool holder is mounted with a close sliding t between the seat I4 and a ledge I8 formed integral with the base I0. One end of the tool holder i6 is recessed to receive a tool 20 (Fig. 1) which is secured in the holder by setscrews 22. As will be described later, the tool holder can be moved in an orbital path, the radius of which is adjustable, so as to turn a circular surface such as indicated at 24 on the workpiece 26. It is understood that the workpiece 26 is carried by a chuck or face plate and turns with the spindle of the lathe.

The tool holder I6 is provided with spaced bores 26 and 30 into which are pressed bushings 32' and 34 respectively. The bushings are adapted to receive eccentric crank pins 36 and 38 which are rotated in synchronism in similar circular paths by turning the handwheel 40, whereby the above-mentioned orbital movement is imparted to tool holder I6.

The pins 36 and 38 are formed at the lower ends of crankshafts 42 and 44 respectively which have tapered Shanks adapted to be seated in similarly tapered sockets formed eccentrically in sleeves 4s and 48. Nuts 50 and 52 which are threaded on the rcrankshafts 42 and 44 respec tively are adapted to be set up against washers 54 and 56 firmly to secure the crankshafts within their respective sleeves. The sleeves 46 and 48 are rotatably mounted in bushings 58 and 60` respectively, the latter being xed in recesses formed in the ledge I8. The sleeves 46 and 48 are rotated simultaneouly in response to a rotation of the handwheel 453 by connections comprising worm gears 62 and 64 and a worm shaft K66 on one end ofv which the handwheel 40 is mounted. The worm shaft 66 is rotatably supported by arms 68 fixed to the base i6 in such a position that the worm on the worm shaftk 66 meshes with the worm gears 62 and 64.

Referring now to Fig. 4, it is apparent that the radius of the orbital movement of the tool holder I6 depends upon the eccenltricity of the pins 36 and 38 with respect to the axis about which the sleeves 46 and 48 rotate. In Fig. 4 let the circles T0, 'l2 and 14 represent the outer periphery of the sleeve 46, the lowermost portion of the tapered section of the crankshaft 42, and the crank pin 36, respectively. The axis about which the sleeve 46 rotates is indicated at 16 and the axis about which the crankshaft 42 is adjustable in rotation with respect to the sleeve 46 is indicated at 78.

It will now be apparent that the total effective eccentricity of the crank pin 36 is equal to the distance from its center to the axis I6 and that this distance may be increased from its minimum as indicated in Fig. 4 by the solid line circle 16 to a maximum as a result of adjusting the crankshaft 42 in rotation with respect with the Sleeve 46 by a half-turn, or to a point indicated by the dotted line position of the circle 14. The device is thus adapted, owing to the provision of the adjustment described above, to turn surfaces of circular cross section, and of various radii within the limits defined by the construction of the device.

Although the adjustment has been described With reference to only one of the cranks, it is to be understood that the same adjustment is made simultaneously in both cranks if any adjustment is made. This adjustment is facilitated by rotating the handwheel 4o luntil slots 8U and 82 formed in the upper ends of the crank shafts 42 and 44 respectively are in alignment. A straight bar is then inserted in both slots. The nuts 5t and 52 are then slightly loosened permitting the sleeves 46 and 48 to be rotated through equal angles with respect to the crankshafts in Vresponse to any given movement of the handwheel dal. Upon setting up the nuts 5l) and 52 and removing the above-mentioned bar from the device, it is again made ready for use under the new condition of adjustment.

The tool holder i6 is adapted to be positively clamped to the base i0, Whenever it is desired to use the tool 26 in the ordinary fashion, by setting up a screw 84. This screw is threaded into the bottom side of the tool holder I6 and has an enlarged head which is seated on the bottom of the base lil. The base is provided with a large hole il@ which is adapted to receive the screw 34 with enough clearance to avoid any interference with the above-described orbital movement of the tool holder'.

While the illustrated device is described herein as adapted to be mounted on the carriage of a lathe and to carry a tool of the type ordinarily used in a lathe, the device may be used equally as well in any machine tool having a carriage to which the base l of the illustrated device can be clamped. Moreover the lathe tool 2G might also be replaced by a separately driven grinding wheel or other type of cutter, for forming a surface of revolution like the surface 24 mentioned above or even a spherical recess in the Work if the work were not rotated.

Another important advantage of the illustrated device results from the fact that the control of the orbital movement of the tool holder is effected at a point remote from the cutting edge of the tool itself. For this reason the illustrated device is well adapted to operate at the bottom of a deep recess, the depth of which is a multiple of its width, because a tool long enough to reach the bottom of such a recess ycan be used without interfering with the sides or open end of the recess.

The invention described herein may be manufactured and used by or for the Government of the United States of America for Government purposes Without the payment of any royalty thereon or therefor.

What is claim is:

1. In a radius forming device, a base, a tool holder mounted for orbital movement on said base, a pair oi sleeves rotatably mounted on said base each of said sleeves having a socket therein formed eccentrically with respect to its axis of rotation, a crank mounted in each of said sockets for adjustment in rotation whereby the eccentricity of said crank can be varied, and means for rotating said sleeves in synchronism with each other, said means comprising gears fixed to said sleeves and a worm meshing with said gears.

2. In a radius forming device, a base, a tool holder mounted on said base to slide in any direction in a plane, a pair of sleeves mounted to rotate on said base, a crank rotatably mounted eccentrically in each of said sleeves, each of said cranks having a pin adapted to be received in said holder, means for clamping said cranks in adjusted position Within said sleeves, and means for rotating said sleeves in synchronism with each other comprising a Worm and worm gears on said sleeves meshing with said worm.

3. In a radius forming device, a base, a tool holder mounted for orbital movement on said base, means for operating said tool holder comprising a member rotatably mounted on said base and having a socket formed eccentrically with respect to its axis of rotation, a crank mounted in said socket and having a pin received in said holder, said pin being disposed eccentrically with respect to said socket, said crank and member being relative adjustable in rotation whereby the eccentricity of said pin with respect to the axis of rotation of said member can be varied, and means for rotating said member.

4. A radius forming attachment for a machine tool comprising, a base, a tool holder mounted for orbital movement on said base, a pair of sleeves rotatably mounted on said base, each of said sleeves having a socket therein formed eccentrically with respect to its axis of rotation, crank members rotatably mounted in each of said sockets, each of said crank members having a tapered shank seated in one of said sockets and a pin disposed concentrically with respect to said socket, said pins being received by said holder, said crank members and said sleeves being rotatable relative to each other whereby the eccentricity of said pins with respect to the axis of rotation of said sleeves can be varied, and means for rotating said sleeves.

JOSEPH G. GOULETTE.

REFERENCES CITED The following references are of record in the le or this patent:

UNITED STATES PATENTS Number Name Date 1,931,143 Feit Oct. 17, 1933 FOREIGN PATENTS Number Country Date 155,156 Germany Oct. 31, 1904 608,453 France July 28, 1926 

